As to the field of application of the invention, reference is made to European Patent publication number 0 342 146 and German Patent P 3618316.
The German patent comprises an energy consumption data recording and transmitting device essentially designed to be applied in preset energy user areas to meter the respective energy consumptions relying upon energy flows linked to the line by means of spatially distributed meters, transmitted through a remote read-out station at the energy consumer to the energy supplier through a transmission line, moreover recording energy-related breakdown report data through breakdown report transmitters connected to the remote read-out station, which can be transmitted, as energy consumption data, in the opposite direction and in synchrony with the energy flows through the transmission path to the energy supplier.
The disadvantage of this system is that it has to be used in preset user areas, and also requires a transmission line for information exchange between the energy consumer and the supplier of such energy, to which end the remote read-out unit is intelligent and is linked to circuits that must take synchrony into account when transmitting data, which means that this system is extremely complex and uneconomical.
Another disadvantage of the system of the German patent lies in the rigidness of the system, for the intelligent remote readout unit has little capacity to be connected to users, thus making it very difficult to increase the number thereof, unless new intelligent read-out units are incorporated to the system, this being very difficult and leading to excessive additional costs.
Therefore, the device of the German patent is complex and uneconomical.
As to the European patent, such comprises an apparatus to establish communication between an electricity meter, comprising a control circuit through which meter data are provided as output signals, and a manipulable communicator, which meter and the communicator are located within a surrounding of direct and indirect radiation generated by the sun.
Therefore, in the European patent, communication between the meter control circuit and the manipulable communicator, is established at some distance and by infrared rays; to which end it has infrared ray transmission and receiving circuits, thus obliging the apparatus to incorporate additional circuits that can detect the incidence of indirect light caused by the sun within the selected spectrum region, leading to a characteristic output of continuous current whose level corresponds to the intensity thereof, so that only the information sent by the manipulable communicator is detected.
Furthermore, as the apparatus in the European patent has photosensitive receiving means within the meter at the rear portion of the front plate thereof, this latter must be configured so as to have a hole in line with a photodiode and configured to substantially restrict direct access of incident radiation to radiation from sources located under a horizontal plane that extends from the highest portion of the photodiode.
The apparatus of the European patent is therefore complex and uneconomical, apart from reading the electric meter at a short distance.
Tests are also known to have been made to read meters by radio, to which end the meters are connected to an intelligent unit which is itself connected to a transmitter receiver to send out the meter data to a mobile unit present in a vehicle, such comprising a transmitter receiver and a computer.
All the meter equipment feeds directly from the mains and needs a coder to read the meter dial positions, such coder being activated for a short space of time (350 ms) to read the meter dial position and convey this information to the meter microprocessor. The format is a pair parity asynchronous ASCII code serial current. In addition to the meter values, the coder provides a signal to detect unauthorized manipulation that can activate broken wires, magnetic field sensors, voltage loss detectors, and so on. After the message is over, the coder is switched off.
All of this represents a complex and costly system, in addition to posing the typical problems involved in using the mains as feed source.